The present invention relates to an impact sensing apparatus, and in particular to an impact sensing apparatus used as a sensor for starting the operation of a safety system such as an air bag or seatbelt tensioner to protect against impact.
A conventional impact sensing apparatus of the type is disclosed in the United States Patent issued under the number of U.S. Pat. No. 5,142,922. This impact sensing apparatus has a housing, a weight freely rotatably and movably supported within the housing at a position offset from the centroid of the weight, a firing lever pivoted to the housing for engaging with the weight, and a spring stretched between the housing and the firing lever for continuously biasing the firing lever in a direction which engages it with the weight.
However, in the foregoing structure, the direct mounting of each of the weight, the firing lever, and the spring to the housing is inevitable, which leads that it is very cumbersome to assemble the conventional impact sensing apparatus. Therefore, the conventional impact sensing apparatus, though it is excellent in concept, fails to comply with requirements for the mass production.